Daicel Chemical Industries, Ltd.

Kazuhiro Nishioka

Tokuji Tanaka

The starting pyroxylin is subjected to an acetylation reaction while it is dispersed in a dispersion medium such as toluene and kept in a solid phase state, and acetylated pyroxylin is then separated from a reaction solution by means of filtration, so that an extra portion of anhydrous acetic acid taking no part in the reaction can be immediately recovered. This dispenses with the precipitation process required for a prior art solution reaction, and so eliminates an unstable quality factor due to product particle size variations. In addition, the process of washing the post-reaction crude acetylated pyroxylin is designed to include a washing step at a high temperature of 60&deg; C. to 105&deg; C. and a washing step using a stabilizer-containing washing agent, so that acetylated pyroxylin having improved heat resistance and stability can be provided.

Acetylated pyroxylin

The starting pyroxylin is subjected to an acetylation reaction while it is dispersed in a dispersion medium such as toluene and kept in a solid phase state, and acetylated pyroxylin is then separated from a reaction solution by means of filtration, so that an extra portion of anhydrous acetic acid taking no part in the reaction can be immediately recovered. This dispenses with the precipitation process required for a prior art solution reaction, and so eliminates an unstable quality factor due to product particle size variations. In addition, the process of washing the post-reaction crude acetylated pyroxylin is designed to include a washing step at a high temperature of 60 to 105&deg; C. and a washing step using a stabilizer-containing washing agent, so that acetylated pyroxylin having improved heat resistance and stability can be provided.

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Himeji, Japan

Kazuhiro Nishioka